Update favicon to red square emoji

Changed the favicon from default to a simple red square (🟥) that matches the site's accent color and minimalist aesthetic.

Changes:
- Created favicon.svg (red square with rounded corners)
- Generated favicon.png (32x32 red square)
- Generated favicon.ico (32x32 red square for legacy browsers)
- Updated layout.tsx to reference both SVG and PNG versions

Color: #ef4444 (matches site accent color)

The red square provides:
✓ Strong brand recognition
✓ Matches minimalist design philosophy
✓ Stands out in browser tabs
✓ Emoji-like simplicity
✓ Consistent with accent color theme

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

public/favicon.svg

@@ -0,0 +1,3 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
+  <rect width="100" height="100" fill="#ef4444" rx="8"/>
+</svg>

src/app/layout.tsx

@@ -34,7 +34,10 @@ export const metadata: Metadata = {
     },
   },
   icons: {
-    icon: "/favicon.png",
+    icon: [
+      { url: "/favicon.svg", type: "image/svg+xml" },
+      { url: "/favicon.png", type: "image/png", sizes: "32x32" }
+    ],
     apple: "/favicon.png",
   },
 };